Recently, conserved quantities have been used for establishing unique continuation properties for solutions of the Dullin-Gottwald-Holm equation [1]} (see also its correction [2]}); the BBM equation [3]}; 0-Holm-Staley equation [4]}, [5]}, [6]}; a generalisation of the CH equation [7]}; and a geometrically integrable equation [8]}. All of these references are concerned to equations, while in [9]} the conservation of norms of solutions of a bi-Hamiltonian system (that has the CH as a particular case) was used to establish unique continuation of its solutions, giving a strong indication that the results (and approaches) considered in [10]}, [1]}, [2]} could be generalised and extended to systems of differential equations or for equations like (REF ) depending on a finite jet of the solution \({\bf u}\) .
